Method, device and equipment for controlling dry state to wet state of thermal power unit and storage medium

Abstract

This invention discloses a control method, apparatus, equipment, and storage medium for the dry-to-wet transition of a thermal power unit. The method includes: upon detecting that the thermal power unit has entered the dry-to-wet operation phase, controlling the fuel quantity to be introduced into the boiler of the thermal power unit according to the electrical load of the thermal power unit at a preset deceleration rate; when the electrical load of the thermal power unit is within the preset electrical load range and the liquid level in the water tank of the thermal power unit is greater than or equal to a first preset liquid level height, sending commands to open the inlet electric valve and the outlet electric valve of the boiler recirculation pump; and when the liquid level in the water tank reaches a second preset liquid level height, sending a command to start the recirculation pump. The technical solution provided by this invention can, to a certain extent, improve the stability of ultracritical (supercritical) units during the dry-to-wet transition process.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of thermal power generation, in particular to a control method, device, equipment and storage medium for dry-to-wet state conversion of a thermal power unit. BACKGROUND

[0002] The process of boiler wet-to-dry state conversion in the process of deep peak regulation of a (super) supercritical once-through boiler is a relatively special stage. During the process, important index parameters such as main steam pressure, steam temperature, superheat degree and water tank level change. If the state conversion fails, it will cause unstable conditions such as large change of main steam temperature and dramatic fluctuation of water tank level, which will seriously affect the safe operation of the unit. In the prior art, the boiler shutdown process still adopts a traditional manual mode. When the unit is running at 30% BMCR (Boiler maximum continue rate) load in dry state, the MFT (Main fuel trip) is manually controlled, so that the unit is shut down. The traditional shutdown method causes large fluctuation of the furnace negative pressure, not only causing the high-temperature flame and flue gas to escape, even causing fire, but also causing large change of water wall tube stress, water wall cracking and even pipe explosion. SUMMARY

[0003] Therefore, the embodiments of the present application provide a control method, device, equipment and storage medium for dry-to-wet state conversion of a thermal power unit, which can improve the stability of the (super) supercritical unit during the dry-to-wet state conversion process to a certain extent.

[0004] In one aspect, the present application provides a control method for auxiliary machine fault load reduction, which comprises: in the case that it is monitored that a thermal power unit enters a dry-to-wet state operation stage, according to the electric load of the thermal power unit, controlling the fuel quantity to be put into the boiler of the thermal power unit at a preset slow-down rate; in the case that the electric load of the thermal power unit is within a preset electric load range, and the water tank level of the thermal power unit is greater than or equal to a first preset liquid level height, sending an opening boiler recirculation pump inlet electric door instruction and an opening boiler recirculation pump outlet electric door instruction; in the case that the water tank level reaches a second preset liquid level height, sending a starting recirculation pump instruction.

[0005] In one embodiment, the control method for dry-to-wet state conversion of a thermal power unit further comprises: in the case that it is monitored that the thermal power unit enters the dry-to-wet state operation stage, sending a large oil gun putting-in-boiler instruction.

[0006] In one embodiment, the method for controlling the transition of the thermal power generating unit from the dry state to the wet state further comprises: obtaining the electric load of the thermal power generating unit, the water tank liquid level, the control state of the intermediate point temperature, and the operation mode of the boiler; sending an enabling signal for the transition of the thermal power generating unit from the dry state to the wet state, when the electric load is less than a preset electric load, the water tank liquid level is less than a third preset liquid level, the control state of the intermediate point temperature is in an automatic control state, and the operation mode of the boiler is in a dry state operation; the enabling signal is used to indicate that the current thermal power generating unit enters the dry state to wet state operation stage.

[0007] In one embodiment, the method for controlling the transition of the thermal power generating unit from the dry state to the wet state further comprises: sending a 361 valve opening instruction of the thermal power generating unit when the water tank liquid level reaches a second preset liquid level; wherein the 361 valve opening instruction comprises a preset opening degree of the 361 valve; monitoring the water flow velocity of the 360 valve of the thermal power generating unit; and adjusting the state of the 361 valve of the thermal power generating unit to an automatic control state when the water flow velocity reaches a preset flow velocity.

[0008] In one embodiment, the method for controlling the transition of the thermal power generating unit from the dry state to the wet state further comprises: adjusting the state of the 361 valve of the thermal power generating unit to a manual control state if the difference between the opening degree of the 361 valve and the preset opening degree is greater than a preset threshold; and / or adjusting the state of the 361 valve of the thermal power generating unit to a manual control state if the difference between the water tank liquid level and the preset water tank liquid level is greater than a preset threshold.

[0009] In one embodiment, the thermal power generating unit comprises a water tank liquid level signal quality judgment module, and the method for controlling the transition of the thermal power generating unit from the dry state to the wet state further comprises: adjusting the state of the 361 valve of the thermal power generating unit to a manual control state if the water tank liquid level is judged by the water tank liquid level signal judgment module as having poor signal quality; and the signal judgment module is used to judge the water tank liquid level signal judgment module as having poor signal quality if the water tank liquid level signal quality is less than or equal to a preset quality fraction.

[0010] In one embodiment, the step of controlling the fuel quantity to be put into the boiler of the thermal power generating unit according to the electric load of the thermal power generating unit at a preset slow-down rate comprises: determining a target fuel quantity to be put into the boiler of the thermal power generating unit at the next time according to the current fuel quantity and the preset slow-down rate; determining a target feed water quantity required by the thermal power generating unit at the next time according to the target fuel quantity; putting fuel into the boiler of the thermal power generating unit according to the target fuel quantity; and supplying water to the thermal power generating unit according to the target feed water quantity.

[0011] In one embodiment, the method for controlling the dry state to wet state of the thermal power generating unit further comprises: controlling the opening degree of the turbine regulating door of the thermal power generating unit, so that the main steam pressure of the thermal power generating unit is within a preset pressure range.

[0012] Another aspect of the present application provides a device for controlling the dry state to wet state of a thermal power generating unit, which comprises: a fuel reduction input unit, configured to, when it is monitored that the thermal power generating unit enters a dry state to wet state operation stage, control the fuel input into the boiler of the thermal power generating unit according to the electric load of the thermal power generating unit, and the fuel is input into the boiler of the thermal power generating unit at a preset reduction rate; a first instruction sending unit, configured to, when the electric load of the thermal power generating unit is within a preset electric load range, and the liquid level of the water storage tank of the thermal power generating unit is greater than or equal to a first preset liquid level height, send an opening instruction of the boiler recirculation pump inlet electric door and an opening instruction of the boiler recirculation pump outlet electric door; and a second instruction sending unit, configured to, when the liquid level of the water storage tank reaches a second preset liquid level height, send a start instruction of the recirculation pump.

[0013] By reducing the fuel input into the boiler of the thermal power generating unit at a preset reduction rate, and opening the inlet and outlet electric doors of the boiler recirculation pump in time when the boiler is in the state transition operation, and starting the recirculation pump when the liquid level of the water storage tank reaches a preset liquid level height, the cooling flow of the boiler recirculation pump can be ensured, and vaporization can be prevented, so that the main steam temperature, the main steam pressure and the unit output of the thermal power generating unit can be prevented from changing greatly, and the smooth transition of the dry state to wet state of the thermal power generating unit can be ensured. BRIEF DESCRIPTION OF DRAWINGS

[0014] The features and advantages of the present application will be more clearly understood from the following detailed description taken in conjunction with the accompanying drawings, which are given by way of illustration and are not to be considered limiting of the present application, in which:

[0015] Figure 1 A schematic diagram of the steps of the method for controlling the dry state to wet state of the thermal power generating unit in one embodiment of the present disclosure is shown;

[0016] Figure 2 A schematic diagram of the start-up system of the once-through boiler in one embodiment of the present disclosure is shown;

[0017] Figure 3 A logic judgment diagram of the input of the large oil gun for stable combustion into the boiler before the dry state to wet state in one embodiment of the present disclosure is shown;

[0018] Figure 4 A logic judgment diagram of the opening of the electric doors before and after the start of the boiler water circulation pump during the transition of the dry state to wet state in one embodiment of the present disclosure is shown;

[0019] Figure 5A logic diagram showing automatic and manual control switching of the valve 361 after the valve 361 is opened in one embodiment of the present disclosure

[0020] Figure 6 A schematic diagram of a control device for dry-to-wet state conversion of a thermal power unit in one embodiment of the present disclosure is shown.

[0021] Figure 7 A schematic diagram of the structure of an electronic device in one embodiment of the present disclosure is shown. DETAILED DESCRIPTION

[0022] To make the purposes, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present disclosure will be described clearly and completely below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present disclosure, rather than all the embodiments. Based on the embodiments in the present disclosure, all other embodiments obtained by those skilled in the art without creative labor fall within the scope of protection of the present disclosure.

[0023] In recent years, as the proportion of renewable energy in the energy structure in China continues to increase, the accommodation capacity of the power grid for renewable energy has also increased, but the contribution of renewable energy to power grid peak regulation is limited, which highlights the importance of coal-fired power units with good peak regulation capacity in the process of power grid peak regulation. This means that under the double pressure of large-scale absorption of renewable energy by the power grid and overcapacity of coal-fired power units, coal-fired power units become the basic energy for flexible peak regulation of the power grid and shoulder the arduous task of power grid peak regulation. At present, affected by the large peak-valley difference of the power grid, the form of peak regulation of coal-fired units is also changing, especially the ultra-basic peak regulation range of coal-fired units has become normalized, gradually forming a deep peak regulation operation mode of coal-fired units.

[0024] In order to help the country achieve the goal of carbon peak and carbon neutralization smoothly, the National Development and Reform Commission and the Energy Bureau issued the "National Coal-fired Power Unit Transformation and Upgrading Implementation Plan" in 2021, which clearly proposes that newly-built coal-fired power units and active units after flexible transformation should have a pure condensing peak regulation capacity of 35% Pe and a heat and power cogeneration heating unit of 40% Pe. However, the current design and debugging of coal-fired unit coordinated control strategy is difficult to meet the requirements of deep peak regulation of the unit, especially for ultra-supercritical units, the dry-wet state conversion of once-through boilers becomes a difficult point for deep peak regulation. In order to strive for the benefits of deep peak regulation of the unit, some regions study the feasibility of low-load stable combustion operation of the unit from 35% Pe to 25% Pe, constantly breaking the limit of deep peak regulation of the unit.

[0025] The process of wet state to dry state operation of a supercritical or ultra-supercritical once-through boiler in a deep load regulation process is a special stage. The process is a mutual conversion process of working fluid circulation flow and forced flow. During the process, important index parameters such as main steam pressure, steam temperature, superheat degree and water tank liquid level change. If the state conversion fails, the main steam temperature changes greatly, the water tank liquid level fluctuates greatly and other unstable conditions occur, which seriously affect the safe operation of the unit. The present application designs a control strategy for wet state to dry state conversion of a deep load regulation supercritical or ultra-supercritical once-through boiler. In actual engineering application, the important parameters of the boiler during the state conversion are stable, and good application effects are obtained.

[0026] Taking a 1000MW ultra-supercritical thermal power unit as an example, the steam-water system of the coal-fired unit is configured with two 50% BMCR steam-driven feedwater pumps and one 30% BMCR electric feedwater pump. The main steam temperature is adjusted by adjusting the water-coal ratio and two-stage desuperheating water, and the reheat steam temperature is adjusted by adjusting the burner swing angle and emergency desuperheating water. The unit starting system has a boiler water circulating pump which is connected in series with the feedwater main pipe, and the inlet working medium comes from the feedwater main pipe and the downcomer. During the unit starting process, as the load increases, the feedwater flow increases, and the proportion of the feedwater at the inlet of the boiler water circulating pump also gradually increases, so as to maintain the circulating pump net suction head and cooling flow.

[0027] Referring to Figure 1 The control method for dry state to wet state conversion of a thermal power unit provided by one embodiment of the present disclosure can include the following steps.

[0028] S110: In the case that the thermal power unit enters a dry state to wet state operation stage is monitored, according to the electrical load of the thermal power unit, the fuel quantity is controlled to be put into the boiler of the thermal power unit at a preset slow-down rate.

[0029] In the embodiment, since there is no obvious steam-water boundary line in the supercritical or ultra-supercritical once-through boiler, when the fuel and water quantity ratio is out of balance, the operating state of the boiler will change from dry state to wet state. During the state conversion process, there is no strict corresponding relationship between the unit load value and the steam parameters. For the supercritical or ultra-supercritical once-through boiler, in order to ensure that the water-cooled wall of the boiler downcomer has sufficient cooling water at low load of the unit, the water-cooled wall does not overheat, and the water flow of the water-cooled wall is not lower than the minimum flow of the boiler, and the separation capacity of the boiler starting separator is also considered. In order to prevent the superheater from being filled with water and cause the main steam temperature to drop greatly, the dry state to wet state conversion process is usually carried out at 30% Pe of the unit load. When the thermal power unit operates in the dry state to wet state, the unit load value is 300MW-265MW. Before the state conversion, the main parameters such as unit load, steam pressure and feedwater flow should be kept stable.

[0030] Referring to Figure 2In the embodiment, after the start of the once-through boiler system, under normal working conditions, the feedwater pipeline passes through the economizer (1), the water-cooled wall (2), and the start-up separator (3 and 4), and when the system is in dry operation, the feedwater to the start-up separator (3 and 4) in the figure is high-temperature and high-pressure main steam, which passes through the superheater (8 and 10) and the desuperheater (9) to the steam turbine (11) to do work; when the boiler is in dry operation and is switched to wet operation, when the water level in the water storage tank (5) is 5 m, the boiler water circulation pump (6) is started, and at the same time, the boiler 361 valve (12) in the figure is slowly opened to 5% opening, until the flow of the 360 valve (7) is 250 t / h, the valve automatic adjustment of the 361 valve (12) is put into operation.

[0031] In the embodiment, the fuel quantity is slowly reduced, and when the boiler is switched to wet operation, because the boiler fuel combustion has a large hysteresis, the fuel reduction process should be performed slowly, and under the condition that the coal quality remains unchanged, the fuel quantity can be slowly reduced by 4 t / h for each 10 MW load. After the switching is completed, the fuel quantity is reduced by about 20 t / h according to the operation experience value.

[0032] In the embodiment, the air quantity can also be reduced correspondingly by reducing the air-coal ratio, so as to reduce the boiler thermal load, and the load of the unit is continuously reduced, and the superheat degree is also slowly reduced.

[0033] S120: In a case where the electric load of the thermal power generating unit is within a preset electric load range, and the water level of the water storage tank of the thermal power generating unit is greater than or equal to a first preset water level height, a start-up boiler recirculation pump inlet electric door opening instruction and a start-up boiler recirculation pump outlet electric door opening instruction are sent.

[0034] In the embodiment, during the dry operation to wet operation of the boiler of the thermal power generating unit or before the switching, the main feedwater pipeline has been switched to the bypass operation, and when the switching is completed, the feedwater bypass valve is in an automatic state, and the feedwater quantity is maintained at 950 t / h or less. Therefore, the boiler recirculation pump inlet electric door and the boiler recirculation pump outlet electric door of the thermal power generating unit are opened in time during the dry operation to wet operation of the thermal power generating unit. Specifically, for example, when the electric load value of the thermal power generating unit is between 260 MW and 302 MW, the thermal power generating unit sends a dry operation to wet operation permission signal, and the water level of the water storage tank is greater than 0.5 m, the three conditions are combined, it is judged that the thermal power generating unit is in the switching region of the dry operation to wet operation, and then the start-up boiler recirculation pump inlet electric door opening instruction, the start-up boiler recirculation pump outlet electric door opening instruction, and the start-up boiler water circulation pump electric door opening instruction are sent.

[0035] S130: In a case where the water level of the water storage tank reaches a second preset water level height, a start-up recirculation pump instruction is sent.

[0036] In the embodiment, when the electric load of the thermal power unit is within the preset electric load range and the water tank liquid level reaches the second liquid level, a start-up recirculation pump instruction is sent. Specifically, for example, after the boiler water tank liquid level rises to the normal water level of 5-7 m, the recirculation pump is started up, which ensures the cooling flow of the boiler circulating pump and prevents vaporization, and from the perspective of energy saving, the boiler water is recovered and the heat loss is reduced.

[0037] Referring to Figure 3 In the embodiment, when the thermal power unit is in the dry state to wet state operation and the electric load of the thermal power unit is between 260 MW and 302 MW and the water tank liquid level is greater than 0.5 m, a front and rear electrically operated door opening instruction of the boiler water circulating pump is sent to open the front and rear electrically operated door of the boiler water circulating pump. Meanwhile, when the thermal power unit is in the dry state to wet state operation and the electric load of the thermal power unit is between 260 MW and 302 MW, when the water tank liquid level reaches 5 m or above, a start-up boiler water circulating pump instruction is sent.

[0038] In one embodiment, the control method of the dry state to wet state of the thermal power unit can further include: sending a boiler large oil gun input instruction when it is monitored that the thermal power unit enters the dry state to wet state operation stage.

[0039] In the embodiment, when it is monitored that the thermal power unit is about to enter the dry state to wet state operation, a large oil gun input instruction is sent to stabilize the boiler combustion of the thermal power unit. If the unit load drops below the minimum stable combustion load, the number of input stable combustion oil guns is appropriately increased to maintain stable combustion in the furnace. The dry state to wet state conversion of the boiler is a smooth transition process, and the superheat degree, water tank water level, main steam pressure and main steam temperature are used to judge whether the switching process is successful. The main steam temperature, main steam pressure and unit output are avoided from changing greatly during the switching process.

[0040] In one embodiment, the control method of the dry state to wet state of the thermal power unit can further include: obtaining the electric load, the water tank liquid level, the control state of the intermediate point temperature and the boiler operation mode of the thermal power unit; sending an allow signal of the dry state to wet state operation of the thermal power unit when the electric load is less than a preset electric load, the water tank liquid level is less than a third preset liquid level, the control state of the intermediate point temperature is in an automatic control state, and the boiler operation mode is in a dry state operation.

[0041] Referring to Figure 4 In the embodiment, when the thermal power unit load is less than 305 MW, the water tank liquid level is less than 1 m, the intermediate point temperature is in an automatic control state, and the boiler is in a dry state mode, the four conditions are combined to judge that the boiler is about to start the state conversion, and then a boiler large oil gun input instruction is sent through the control strategy.

[0042] In one embodiment, the method for controlling the transition of the thermal power generating unit from dry state to wet state can further comprise: sending a 361 valve opening instruction of the thermal power generating unit when the water tank level reaches a second preset level; wherein the 361 valve opening instruction comprises a preset opening degree of the 361 valve; monitoring the water flow rate of the 360 valve of the thermal power generating unit; and adjusting the state of the 361 valve of the thermal power generating unit to an automatic control state when the water flow rate reaches a preset flow rate.

[0043] In the present embodiment, the opening degree of the 361 valve is slowly opened to the preset opening degree by the enhanced soft hand controller when the water tank level reaches the second preset level. When the water flow rate through the 360 valve reaches 250 t / h, the enhanced soft hand controller is requested to put the 361 valve into automatic adjustment, and the 361 valve is put into automatic. Specifically, for example, when the water tank level reaches 5 m (the second preset level) or above, the enhanced soft hand controller slowly opens the 361 valve to 5% of the opening degree (the preset opening degree of the 361 valve), and when the water flow rate through the 360 valve reaches 250 t / h or above, the enhanced soft hand controller is requested to put the 361 valve into automatic adjustment, and the 361 valve is put into automatic.

[0044] In one embodiment, the method for controlling the transition of the thermal power generating unit from dry state to wet state can further comprise: adjusting the state of the 361 valve of the thermal power generating unit to a manual control state if the difference between the opening degree of the 361 valve and the preset opening degree is greater than a preset threshold; and / or adjusting the state of the 361 valve of the thermal power generating unit to a manual control state if the difference between the water tank level and the preset water tank level is greater than a preset threshold.

[0045] In the present embodiment, in some cases, the error between the opening degree of the 361 valve and the opening degree of the valve in the 361 valve opening instruction exceeds the preset threshold due to the mistakes of the operators or the uncontrolled system and the like. Alternatively, when the difference between the water tank level and the preset water tank level exceeds the preset threshold, the thermal power generating unit is prevented from malfunctioning due to the water supply. In order to prevent the superheater and the reheater from dropping too fast, the temperature reducing water regulating valve is appropriately closed, and the boiler feed water flow rate is maintained during the transition to ensure that the feed water flow rate is not lower than the protection set value, and the thermal power generating unit is not shut down due to the low feed water flow rate. The control mode of the 361 valve needs to be temporarily adjusted to the manual control mode.

[0046] Specifically, for example, refer to Figure 5The water tank liquid level PV value is compared with the water tank liquid level SP value after being filtered in advance and lagged, and is sent to the enhanced EPID control logic block to perform PID operation. The operation instruction is sent to the 361 valve opening degree instruction of the boiler through the enhanced soft hand operation logic block, and the 361 valve is given the corresponding opening degree. At the same time, it is judged whether the difference between the water tank liquid level PV value and the SP value is more than 2.5 m, and whether the difference between the 361 valve opening degree feedback and the opening degree instruction is 15%. When either of the two conditions occurs, the 361 valve regulation is automatically released, and the 361 valve enters the manual regulation mode, and the 361 valve regulation manual mode is displayed.

[0047] In the process of changing from the dry state to the wet state, the starting system of the boiler is drained to the condenser. In order to reduce the influence of the drainage on the vacuum of the condenser, the 361 valve opening degree should be maintained when the boiler is in the wet state, so as to avoid that the large drainage volume affects the vacuum of the condenser.

[0048] In an embodiment, the thermal power generating unit comprises a water tank liquid level signal quality judgment module. The control method of the thermal power generating unit changing from the dry state to the wet state can further comprise: if the water tank liquid level is judged as poor signal quality by the water tank liquid level signal judgment module, adjusting the state of the 361 valve of the thermal power generating unit to the manual control state; and the signal judgment module is used to judge the water tank liquid level signal as poor signal quality when the signal quality is less than or equal to a preset quality fraction.

[0049] In the embodiment, please refer to Figure 5 If an abnormal working condition occurs in the 361 valve regulation process, it is judged that the water tank liquid level PV value measurement quality is bad, and then the 361 valve regulation is automatically released, and the 361 valve enters the manual regulation mode.

[0050] In an embodiment, in the step of controlling the fuel quantity to be put into the boiler of the thermal power generating unit according to the electrical load of the thermal power generating unit at a preset slow-down rate, the step can comprise: determining a target fuel quantity to be put into the boiler of the thermal power generating unit at the next moment according to the current fuel quantity and the preset slow-down rate; determining a target feed water quantity required by the thermal power generating unit at the next moment according to the target fuel quantity; putting fuel into the boiler of the thermal power generating unit according to the target fuel quantity; and supplying water to the thermal power generating unit according to the target feed water quantity.

[0051] In the embodiment, in the process of changing the thermal power generating unit from the dry state to the wet state, the water-cooled wall downcomer and the back wall of the boiler can produce steam-water two-phase flow, which can cause the downcomer wall temperature deviation or temperature overrun due to uneven water power. In this process, the fuel quantity and the feed water quantity should be maintained as stable as possible, and the running time of this region should be shortened as much as possible. The water-coal ratio is controlled to be 7.5-8, so as to avoid the occurrence of dry-wet state alternating working conditions due to the large fluctuation of the feed water flow and the fuel quantity.

[0052] In one embodiment, the method for controlling the transition of the thermal power generating unit from dry state to wet state can further comprise: controlling the opening degree of the turbine governing valve of the thermal power generating unit, so that the main steam pressure of the thermal power generating unit is within a preset pressure range.

[0053] In the embodiment, the main steam pressure of the boiler of the thermal power generating unit is maintained at about 10 MPa during the transition, and as the fuel quantity decreases, the main steam pressure also gradually decreases. At this time, the current main steam pressure can be maintained by appropriately closing the main governing valve through a control strategy, so as to avoid the decrease of the main steam pressure as the unit load decreases. Meanwhile, the decrease amplitude of the unit load value should not be too large, so as to maintain the correction effect of the unit load on the water tank liquid level. As the main steam pressure decreases, the closing of the governing valve is realized in the original DEH logic. The control strategy design increases the rate limit of the decrease of the load value, so as to prevent the decrease of the load from being too large.

[0054] In one specific embodiment, taking a 1000 MW ultra-supercritical unit as an example, during the deep peak shaving process of the unit, the boiler is switched from dry state operation to wet state operation. When the boiler load decreases to below 30% Pe and the main steam pressure decreases to about 10 MPa, the fuel quantity is slowly reduced through a control strategy, the water tank liquid level of the boiler rises, and the boiler is switched to wet state operation.

[0055] When the unit load decreases to 30% Pe during the transition of the boiler from dry state operation to wet state operation, the boiler maintains the operation of 3 pulverizing systems. If the unit load continues to decrease, one less pulverizing system should be put into operation, the feed water flow rate is maintained at 950 t / h, and if necessary, the bottom layer large oil gun is put into operation to stabilize the boiler combustion. During this process, the coal quantity of the pulverizing system is gradually reduced, the water tank liquid level gradually rises, and the 361 valve is slowly opened. When the water tank liquid level is about 5 m, the 361 valve is automatically put into operation to maintain the current water tank liquid level. It should be noted that during this process, if the unit load decreases below the minimum stable combustion load, the number of the stable combustion oil guns put into operation should be appropriately increased to maintain the stable combustion in the furnace. The transition of the boiler from dry state to wet state is a smooth transition process, and the overheat degree, the water tank liquid level, the main steam pressure and the main steam temperature are used to judge whether the switching process is successful. During the switching process, the main steam temperature, the main steam pressure and the unit output should not be greatly changed.

[0056] In addition, in the process of dry state to wet state, the starting system of the boiler drains to the condenser, in order to reduce the influence of the drainage on the vacuum of the condenser, the valve opening degree 361 should be maintained during the wet state operation of the boiler to avoid excessive drainage affecting the vacuum of the condenser. During the conversion zone operation, the water-cooled wall downcomer and the back wall of the boiler may produce steam-water two-phase flow, which may cause the downcomer wall temperature deviation or temperature overrun due to uneven water power. During this process, the fuel quantity and the feedwater quantity should be maintained as stable as possible, and the operation time of this zone should be shortened as much as possible, and the water-coal ratio should be controlled to be less than 7.5 to 8 to avoid the dry-wet state alternating condition caused by the large fluctuation of the feedwater flow and the fuel quantity.

[0057] Because the boiler state conversion process is a special operating condition during operation, various main parameters will change, if the water-coal ratio and the main steam pressure control are improper, the main steam pressure, the main steam temperature, the superheat degree and other main parameters will fluctuate sharply, which will affect the safe operation of the unit. According to the characteristics of the dry-wet state conversion of the ultra-supercritical once-through boiler, considering various risks that may occur during the state conversion process, a wet state to dry state control strategy for the deep peak shaving ultra-supercritical thermal power unit is developed, which not only realizes the automatic process of the dry state to wet state operation and reduces the operation intensity of the operating personnel, but also improves the automation level of the unit, so that the unit can quickly complete the wet state to dry state operation process under the deep peak shaving condition, and avoid the unstable condition of the main parameters caused by improper adjustment during the state conversion process.

[0058] Referring to Figure 6 One embodiment of the present disclosure further provides a control device for dry state to wet state of a thermal power unit, which can include: a fuel slow input unit, a first instruction sending unit, and a second instruction sending unit.

[0059] The fuel slow input unit is used for, in the case of monitoring that the thermal power unit enters a dry state to wet state operation stage, controlling the fuel quantity to be input into the boiler of the thermal power unit at a preset slow rate according to the electric load of the thermal power unit.

[0060] The first instruction sending unit is used for, in the case that the electric load of the thermal power unit is within a preset electric load range and the liquid level of the water storage tank of the thermal power unit is greater than or equal to a first preset liquid level height, sending an opening instruction of a boiler recirculation pump inlet electric door and an opening instruction of a boiler recirculation pump outlet electric door.

[0061] The second instruction sending unit is used for, in the case that the liquid level of the water storage tank reaches a second preset liquid level height, sending a starting instruction of a recirculation pump.

[0062] The specific functions and effects of the control device for the dry state to wet state transition of the auxiliary thermal power generating unit can be explained in reference to other embodiments of the present disclosure, and will not be repeated here. Each module in the control device for the dry state to wet state transition of the thermal power generating unit can be implemented in whole or in part by software, hardware, or a combination thereof. The modules can be embedded in or independent of the processor in the computer device in hardware form, or stored in the memory of the computer device in software form, so as to be called and executed by the processor to perform the operations corresponding to each module.

[0063] Referring to Figure 7 The electronic device includes a processor and a memory. The memory is configured to store a computer program. When the computer program is executed by the processor, the control method for the dry state to wet state transition of the thermal power generating unit is implemented.

[0064] The processor can be a central processing unit (CPU). The processor can also be other general-purpose processors, digital signal processors (DSPs), application specific integrated circuits (ASICs), field programmable gate arrays (FPGAs) or other programmable logic devices, discrete gates or transistor logic, discrete hardware components, or a combination thereof.

[0065] The memory is a non-transitory computer readable storage medium, and can be used to store non-transitory software programs, non-transitory computer executable programs and modules, such as program instructions / modules corresponding to the method in the embodiments of the present disclosure. The processor executes various functions and data processing of the processor by running the non-transitory software programs, instructions and modules stored in the memory, i.e. implements the method in the method embodiments.

[0066] The memory can include a program storage area and a data storage area. The program storage area can store an operating system and at least one application required by a function. The data storage area can store data created by the processor, etc. In addition, the memory can include a high-speed random access memory, and can also include a non-transitory memory, such as at least one magnetic disk storage device, a flash memory device, or other non-transitory solid-state memory device. In some embodiments, the memory can optionally include a memory remotely arranged with respect to the processor, and these remote memories can be connected to the processor through a network. Examples of the network include but are not limited to the Internet, an intranet, a local area network, a mobile communication network, and a combination thereof.

[0067] The one embodiment of the present disclosure further provides a computer readable storage medium for storing a computer program, which, when executed by a processor, implements the control method of the dry state to the wet state of the thermal power generating unit.

[0068] Those skilled in the art can understand that all or part of the processes in the above-mentioned embodiments can be completed by a computer program instructing related hardware. The computer program can be stored in a non-volatile computer readable storage medium, and when executed, can include the processes of the above-mentioned embodiments. Any reference to memory, storage, database or other medium in the embodiments provided in the present specification can include at least one of non-volatile and volatile memory. The non-volatile memory can include read-only memory (ROM), magnetic tape, floppy disk, flash memory or optical memory. The volatile memory can include random access memory (RAM) or external cache memory. As an illustration but not limitation, the RAM can be in various forms, such as static random access memory (SRAM) or dynamic random access memory (DRAM).

[0069] It should be understood that each flow and / or block in the flowchart and / or block diagram, and a combination of flows and / or blocks in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing apparatus to produce a machine, so that the instructions executed by the processor of the computer or other programmable data processing apparatus produce a device that implements the flow Figure 1 The device that implements the function specified in one flow or multiple flows and / or blocks Figure 1 The device that implements the function specified in one flow or multiple flows and / or blocks

[0070] The embodiments in the present specification are described in a progressive manner. Different embodiments focus on describing the parts that are different from other embodiments. Those skilled in the art can understand the embodiments in the present specification and the technical features disclosed by the embodiments after reading the present specification, and more combinations can be made. In order to make the description simple, not all possible combinations of technical features in the embodiments are described. However, as long as the combinations of technical features do not contradict, they should be considered as the scope disclosed in the present specification.

[0071] It is also to be noted that the terms "comprising", "including", and any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but can also include other elements not expressly listed or inherent to such process, method, article, or apparatus. An element proceeded by "comprises a... " does not, without more constraints, exclude the existence of additional identical elements in the process, method, article, or apparatus that comprises the recited element.

[0072] The various embodiments in the present specification are focused on differentiating parts from other embodiments, and each embodiment can be interpreted in contrast with other embodiments. Any combination of the various embodiments in the present specification, based on common general knowledge used by those skilled in the art, is covered by the scope of the disclosure in the present specification.

[0073] The above description is only some embodiments of the present application, and is not intended to limit the scope of protection of the claims of the present application. For those skilled in the art, the present application can have various modifications and changes. Any modification, equivalent replacement, improvement, etc. within the spirit and principle of the present application shall be included in the scope of claims of the present application.

Claims

1. A method for controlling a dry to wet state of a thermal power unit, characterized in that, The method comprises: In the case of monitoring that the thermal power generating unit enters a dry state to wet state operation stage, according to the electric load of the thermal power generating unit, the amount of fuel is controlled to be put into the boiler of the thermal power generating unit at a preset slow-down rate; In the case that the electric load of the thermal power generating unit is within a preset electric load range, and the water tank liquid level of the thermal power generating unit is greater than or equal to a first preset liquid level height, an opening boiler recirculation pump inlet electric door instruction and an opening boiler recirculation pump outlet electric door instruction are sent; In the case that the water tank liquid level reaches a second preset liquid level height, a start recirculation pump instruction is sent; The method further comprises: In the case that the water tank liquid level reaches a second preset liquid level height, a 361 valve opening instruction of the thermal power generating unit is sent; wherein the 361 valve opening instruction comprises a preset opening degree of the 361 valve; The water flow velocity of the 360 valve of the thermal power generating unit is monitored; In the case that the water flow velocity reaches a preset flow velocity, the state of the 361 valve of the thermal power generating unit is adjusted to an automatic control state; If the difference between the opening degree of the 361 valve and the preset opening degree is greater than a preset threshold, the state of the 361 valve of the thermal power generating unit is adjusted to a manual control state; And / or, if the difference between the water tank liquid level and a preset water tank liquid level is greater than a preset threshold, the state of the 361 valve of the thermal power generating unit is adjusted to a manual control state; The method further comprises: If an abnormal working condition occurs in the 361 valve adjustment process, it is judged that the water tank liquid level PV value measurement quality is bad, the 361 valve adjustment is automatically released, and the 361 valve enters a manual adjustment mode.

2. The method of claim 1, wherein, The method further comprises: In the case of monitoring that the thermal power generating unit enters a dry state to wet state operation stage, a large oil gun putting instruction for the boiler is sent.

3. The method of claim 2, wherein, The method further comprises: The electric load, the water tank liquid level, the control state of the intermediate point temperature, and the boiler operation mode of the thermal power generating unit are acquired; In the case that the electric load is less than a preset electric load, the water tank liquid level is less than a third preset liquid level height, the control state of the intermediate point temperature is in an automatic control state, and the boiler operation mode is in a dry state operation, an allow signal of the dry state to wet state operation of the thermal power generating unit is sent; the allow signal is used to represent that the current thermal power generating unit enters a dry state to wet state operation stage.

4. The method of claim 1, wherein, The thermal power generating unit comprises a water tank liquid level signal quality judgment module, and the method further comprises: If the water tank liquid level is judged by the water tank liquid level signal judgment module as poor signal quality, the state of the 361 valve of the thermal power generating unit is adjusted to a manual control state; the signal judgment module is used to judge the water tank liquid level signal as poor signal quality in the case that the water tank liquid level signal quality is less than or equal to a preset quality fraction.

5. The method of claim 1, wherein, In the step of controlling the amount of fuel to be put into the boiler of the thermal power generating unit at a preset slow-down rate according to the electric load of the thermal power generating unit, comprising: According to the current fuel amount and the preset slow-down rate, a target fuel amount put into the boiler of the thermal power generating unit at the next time is determined; According to the target fuel amount, a target feed water amount required by the thermal power generating unit at the next time is determined; According to the target fuel amount, fuel is fed into a boiler of the thermal power unit, and according to the target feed water amount, feed water is supplied to the thermal power unit.

6. The method of claim 1, wherein, The method further comprises: Controlling the opening degree of a turbine governing valve of the thermal power unit, so that the main steam pressure of the thermal power unit is within a preset pressure range.

7. A control device for a dry to wet transition of a thermal power unit, characterized in that, The control device for the dry-to-wet state transition of the thermal power unit comprises: A fuel slow-feeding unit is configured to, in a case where it is monitored that the thermal power unit enters a dry-to-wet state transition operation stage, control fuel to be fed into a boiler of the thermal power unit according to a preset slow-feeding rate and according to the electric load of the thermal power unit; A first instruction sending unit is configured to, in a case where the electric load of the thermal power unit is within a preset electric load range and the liquid level of a water storage tank of the thermal power unit is greater than or equal to a first preset liquid level height, send an opening instruction of an inlet electrically-operated door of a boiler recirculation pump and an opening instruction of an outlet electrically-operated door of the boiler recirculation pump; A second instruction sending unit is configured to, in a case where the liquid level of the water storage tank reaches a second preset liquid level height, send a start instruction of the recirculation pump; The device further comprises an adjusting unit configured to: In a case where the liquid level of the water storage tank reaches the second preset liquid level height, send a 361 valve opening instruction of the thermal power unit; wherein the 361 valve opening instruction comprises a preset opening degree of the 361 valve; Monitor the water flow velocity of a 360 valve of the thermal power unit; In a case where the water flow velocity reaches a preset flow velocity, adjust the state of the 361 valve of the thermal power unit to an automatic control state; If the difference between the opening degree of the 361 valve and the preset opening degree is greater than a preset threshold value, adjust the state of the 361 valve of the thermal power unit to a manual control state; And / or, if the difference between the liquid level of the water storage tank and a preset liquid level of the water storage tank is greater than a preset threshold value, adjust the state of the 361 valve of the thermal power unit to a manual control state; The adjusting unit is further configured to: If an abnormal working condition occurs in the 361 valve adjusting process, it is judged that the measurement quality of the liquid level PV value of the water storage tank is bad, the 361 valve adjusting is automatically released, and the 361 valve enters a manual adjusting mode.

8. An electronic device, comprising: The electronic device comprises a processor and a memory, and the memory is used to store a computer program, and the computer program is executed by the processor to implement the method in any one of claims 1 to 6.

9. A computer-readable storage medium, characterized in that, The computer readable storage medium is used to store a computer program, and the computer program is executed by a processor to implement the method in any one of claims 1 to 6.

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